Adding an email account to an iPhone/iPad
1. Open Settings.
2. Click Passwords and Account.
3. Click Add Account.
4. Select Microsoft Exchange as the account type.
5. Enter your email address and description for the account. Click Next.
6. In the window that will open, click Log in.
7. In the browser window that opens, enter your password and press Login.
8. If you are using Multi-Step Authentication (MFA), you will be notified that you have accepted the login. Accept the login in the authentication method you are using.
9. Press Continue. (Apple Internet Accounts means signing in to M365 to use Mail / Email.)
10. Check that the dots are on, and then press Save.
NOTE! In Contacts, under Contacts, Notes, and Calendar, check that the default accounts have been changed to the one you just added. By default, your device stores new contacts or calendar entries in this contact list / calendar.